Gregory S.Thomas, MD, MPH, Section Editor
Mission Internal Medical Group, MissionViejo, CA
Nuclear Cardiology Clinic
The Importance of Heart Rate Response in
Myocardial Perfusion Imaging
Gregory S.Thomas, MD, MPH; Haresh Majmundar, CNMT; Daniel L. Kulick, MD
51-year-old man with chronically low high-
density lipoprotein cholesterol and past
inferior myocardial infarction underwent
Answer
The initial study demonstrates a reversible defect of the
proximal and mid anterior wall, a fixed proximal infe-
rior wall defect, and mild transient cavity dilation. The
fixed defect remains on the subsequent study but the
reversible anterior wall defect is much less prominent
and transient cavity dilation is no longer observed.
A
myocardial perfusion imaging (MPI) following mul-
tiple coronary interventions and ultimately coro-
nary artery bypass surgery. The indication for the
study was mild exertional chest pain. The patient
underwent exercise dual isotope testing with
Thallium 201 and Technetium 99m sestamibi. The
patient exercised for 13 minutes on the standard
Bruce protocol without chest pain or electrocardio-
graphic changes. Perfusion images are shown in
Figure 1.
The intervention was not first or second percutaneous coro-
nary intervention of the proximal left anterior descending
or diagonal. Rather, the patient was placed on long-acting
diltiazem, 180 mg, following the initial study. Peak heart
rate achieved on the first study was 155 bpm, 84% of max-
imal predicted heart rate compared with 139 bpm, 76% of
maximal predicted heart rate, on the subsequent study.
Ten months later the patient underwent a second
dual isotope MPI, exercising for 11 minutes 40 sec-
onds without chest pain and with 1/2 mm of flat ST
depression in V5–6. Perfusion images are shown in
Figure 2.
Conclusion
Medications that limit heart rate,1,2 or that may
result in coronary vasodilation,3 can impact the
extent of ischemic involvement and have important
implications when using MPI for purposes of diag-
nosis or when evaluating of disease extent.
How would you interpret the two studies? What
occurred between the two?
REFERENCES
1
American Society of Nuclear Cardiology. Updated imaging
guidelines for nuclear cardiology procedures, Part 1. J Nucl
Cardiol. 2001;8(1):G5–G58.
Heller GV, Ahmed I, Tilkemeier PL, et al. Influence of exer-
cise intensity on the presence, distribution, and size of thal-
lium-201 defects. Am Heart J. 1992;123(4 pt 1):909–916.
3
Lewin HC, Hachamovitch R, Harris AG, et al. Sustained
reduction of exercise perfusion defect extent and severity with
isosorbide mononitrate (Imdur) as demonstrated by means of
technetium 99m sestamibi. J Nucl Cardiol. 2000;7(4):342–353.
2
ID: 2681
• From the Cardiology Division, Mission Internal Medical Group, MissionViejo, CA
• Address for correspondence: Gregory S.Thomas, MD, MPH, Mission Internal Medicine Group, 26732 CrownValley Parkway, Suite 155, Mission
Viejo, CA 92691; e-mail: gthomas@mimg.com
Summer 2003
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Importance of HR Response in MPI